How easily does it "Bump Start"?
And is it running normally otherwise?
I don't know ANY details about your specific diesel, since we didn't get them over here.
IF it has a mechanical pump injection system, and one of the injectors isn't shutting off completely, enough fuel COULD dribble in there to get a bit of a hydro lock that the bump start clears. After that it would start normally until it sat again for a while...
just a shot in the dark since I don't know what system your engine uses...